Pin hole free 2D Ruddlesden-Popper Perovskite layer with closed packed large crystalline grains, suitable for fast response and high sensitive MSM photodetection

Abstract

Here, we achieved pin hole free 2D Ruddlesden-Popper Perovskite (RPP) BA2PbI4 layers with closed packed crystalline grains with dimension of about 30×30 µm2, which have been demonstrated to be favorable for optoelectronic applications, such as fast response RPP-based metal/semiconductor/metal photodetectors. We explored affecting parameters in hot casting of BA2PbI4 layers, and proved that oxygen plasma treatment prior to hot casting plays a significant role to achieve high quality closed packed polycrystalline RPP layers at lower hot cast temperatures. Moreover, we demonstrate that crystal growth of 2D BA2PbI4 can be dominantly controlled by the rate of solvent evaporation through substrate temperature or rotational speed, while molarity of the prepared RPP/DMF precursor is the dominant factor that determines the RPP layer thickness, and can affect the spectral response of the realized photodetector. Benefiting from the high light absorption and inherent chemical stability of 2D RPP layers, we achieved high responsivity and stability, and fast response photodetection. We achieved a fast photoresponse with rise and fall times of 187 µs and 280 µs, and the maximum responsivity of 119 mA/W and detectivity of 2.15×108 Jones in response to illumination wavelength of 450 nm. The presented polycrystalline RPP-based photodetector benefits from a simple and low-cost fabrication process, suitable for large area production on glass substrate, a good stability and responsivity, and a promising fast photoresponse, even around that of exfoliated single crystal RPP-based counterparts. However, it is well known that exfoliation methods suffer from poor repeatability and scalability, which make them uncompatible with mass production and large area production.